This K08 award will allow an experienced optometrist presently training in vision science to obtain the needed expertise in oculomotor systems, visual optics and neurophysiology to test important hypotheses regarding accommodation and the development of ametropias, in a challenging academic environment. The candidate's long-term career goals are to practice as an independent researcher in the fields of accommodation, eye movements, and visual processing. The immediate goal is to develop the skills to investigate the optical signals that specify ocular focus, the cone types that participate in the process, the visual mechanisms that might mediate the signals (Stiles-Crawford effect and fixation micro-saccades), and the neural pathways and transmit the signals. Essential skills include the ability to build, calibrate and maintain electro-optical systems for monitoring both fixational saccades and accommodation, to measure and alter the Stiles-Crawford function, and to produce computer-generated images that drive accommodation and isolate cone classes or visual pathways. The program will prepare the student to meet these goals through a series of graduate courses and seminars, a program of supervised laboratory experience, experience in presentation and discussion of research findings and teaching, and instruction in responsible conduct of research. A supervised research plan will examine several hypotheses related to these goals: 1. whether S-sensitive cones mediate the signals that drive accommodation; 2. whether L-, M- and S- cones drive accommodation by sensing the angle of incidence of light reaching the retina; 3. whether the dioptric vergence signal for accommodation is mediated by motion pathways for color and/or luminance; 4. whether a decentered Stiles-Crawford function for S-cones mediates a directional signal for accommodation, and 5. whether small fixational eye movements contribute to the signal for reflex accommodation.